On either extreme an engine designer can produce max torque at a lower RPM or a higher RPM. For racing, of course one wants peak torque at hightest RPM whereas peak torque at low RPM results in pulling power for large loads.
Speaking of the reliabliity issue I lament the passing of Dodge's Slant Six. I drove a 1 ton crew cab Dodge pickup with a smallish Slant Six all day long at 100 MPH with absolutely no issues whilst in Uncle Sam's Canoe Club. I did this for months on end. In addition one of my friends worked the counter at a parts house and he told me he never in several years ever sold any rebuild parts for one of those engines.
